摘要:This study evaluates the platelet count changes in neonates with hyperbillirubinemia who received phototherapy. In this Prospective Descriptive-cross sectional study 144 full term newborns with indirect hyperbillirubinemia who received phototherapy in neonatal ward of Bessat hospital in Hamedan province of Iran were studied from September 2007 to February 2008 for evaluation the effect of phototherapy on platelet count. The platelet had counted by cell counter and it had controlled by slide platelet counting. The data were analyzed using spss version. 13 and compared with paired-samples T test. 58 neonates (40.3%) were boys and 86 (59.7%) were girls. The mean age of neonates was 7.04 +/– 5.49 days (2 - 29 days). The mean (± SD) platelet counts were 287833.3 + 92332.4 before and 299444.4 + 98565.2 after phototherapy. Analysis of data with paired T test showed significant difference in platelet count before and after phototherapy. Mean platelet count after phototherapy was higher than that before treatment. The study had propounded that mean platelet count increased with extended mean phototherapy time. This study had propounded this hypothesis that phototherapy in full term icteric newborns leads to increased platelet count. It may be due to accelerated platelet turnover in peripheral microvasculature with adequate platelet reserve.